JUDDERING

Hi my laguna, judders slightly on moving away, in first gear, but when I turn on the air con it gets realy bad, and sometimes stals on take off the higher I turn up the air con the worse the juddering gets on take off, or when idling, have taking it to severial garages, but the can't sort it, could you please offer some advice.

No mil/check engine light on dash, yes the vehicle has been plugged into a diagnostic computer, the results showed no faults anywhere, the garage replaced the engine mounts and the gearbox mounts, that did not make any difference.

I have said this to the garage, about vacum leaks, the said it would have show on the dignostic check, I don't know If this is true, because I don't know very much about how the dignostic system works, or what It can pick up on, someone said the A/C need's to be reprogramed, I don't know what this mean's.
Or if this can be done, or If this would make any differance.

The A/C will not be the cause of the problem ! when A/C is turned on it makes the cars engine work a little harder this in turn makes the fault seem worse ..you cannot reprogramme an A/C compressor .. you can on some vehicles reprogram the controls (ie. if it's automatic A/C) .. Technically a vacuum leak will not show on a diagnostic scan, if it is causing a fault all the time ...it will affect another sensor/system and the technician will have to check all surrounding (related) systems to discover the leak (so the scan will not actually state a vacuum leak is the cause) vacuum leaks will cause misfire symptoms or excess fuel/air ratio etc. etc. .. these will show up on a diagnostic scan and the technician will then have to check what is causing these fault's (is it a vacuum leak/bad CKP/bad plug etc. etc.) a diagnostic scan does not always point at the problem and state "change this part" and all will be good ... also if the problem is intermittent it will not show on a diagnostic scan unless it is present (MIL on) when the scan is done !!

Thank you for your quick reply, It has been very helpfull, I honestly don't think the are ever going to find the prob with this car, It has been in and out of garages for the last year, with the A/C idea I think I was just grabbing at straws, It's time to change the car, again thank's for all your help and advice.